Action of vitamin D metabolites on PTH secretion in man.
We have examined the effects of metabolites of vitamin D [25OHD3, 1,25(OH)2D3, 24,25(OH)2D3, and 25,26(OH)2D3] on serum calcium and iPTH in human deficient-D osteomalacia. The four metabolites decreased iPTH, but only for 1,25(OH)2D3 was a significant correlation between increase of serum calcium and decrease of iPTH observed. The 24,25(OH)2D3 and 25,26(OH)2D3 decreased iPTH despite a decrease of serum calcium at the beginning of treatment. The 25OHD decreased iPTH before increased serum calcium. These results could be interpreted as a direct effect of metabolites of vitamin D on PTH secretion. However, the conversion of other metabolites and the calcium concentration in parathyroid cells must be determined before this hypothesis can be accepted.
D015650:24,25-Dihydroxyvitamin D 3; D000328:Adult; D002112:Calcifediol; D002118:Calcium / Q000032:analysis; D004100:Dihydroxycholecalciferols / Q000494:pharmacology; D006801:Humans; D006887:Hydroxycholecalciferols / Q000494:pharmacology*; D008875:Middle Aged; D010018:Osteomalacia / Q000378:metabolism; D010281:Parathyroid Hormone / Q000032:analysis* / Q000378:metabolism
D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D010281:Parathyroid Hormone; D015650:24,25-Dihydroxyvitamin D 3; D002112:Calcifediol; C026032:25,26-dihydroxycholecalciferol; D002118:Calcium